1. Field of the Invention
Disclosed herein are nanoparticle treated fibrous articles, such as fabrics, fibers, filaments, and yarns, compositions and methods for making nanoparticle treated fibrous articles, and methods of using nanoparticle treated fibrous articles.
2. Relevant Technology
Utilization of various nanoparticle materials into and/or onto fabrics has been used in an attempt to impart characteristic advantages of a given nanoparticle to a given fabric. The term “nanoparticle” often refers to particles of any shape having a largest dimension of less than 100 nm. By way of example, silver (Ag) nanoparticles have been applied to fabrics to provide antimicrobial, antibacterial, or other related properties.
There are several notable problems with existing nanoparticle treated fabrics. For example, without a mechanism for substantially permanent immobilization of nanoparticles onto the fabric, any performance enhancement provided by the nanoparticles is quickly lost. Conversely, if a completely permanent mechanism for nanoparticle immobilization or tethering is used, the characteristics of the nanoparticles can be altered by such immobilization and their efficacy is limited as the nanoparticle is unable to freely interact as it otherwise would as a suspended, non-tethered particle. In addition, covalently bonding nanoparticles to fibers and fabric surfaces is very expensive. If, instead, the nanoparticles are merely encapsulated within a polymer or other binder material, they are generally unavailable for any purpose until the binder sloughs off, wears away, or otherwise exposes the nanoparticles.
The tradeoff between maintaining desired nanoparticle activity, on the one hand, and immobilizing the nanoparticles, on the other, has led to the development of methods for permanently attaching metal nanoparticles to fabrics and using the metal nanoparticles as a source of metal cations that provide the desired effects. This is particularly true in the case of silver (Ag) nanoparticles. Examples include covalently bonding nanoparticles onto the fibers as in U.S. Pat. No. 6,607,994, utilization of electrostatic interactions between the nanoparticles and the fabric as in U.S. Pat. Pub. No. 2009/0098366, and growing silver nanoparticles on the fabric fiber surface as in U.S. Pat. Pub. No. 2011/0110999 Immobilized silver (Ag) nanoparticles can in this way produce silver ions (Ag+) more rapidly than when using silver (Ag) threads or other macro-sized silver (Ag) components, and in a significantly more controlled manner than impregnation of fabric with silver (Ag) salts.
Regardless of the specific results or efficacy of any of these prior art solutions, each ultimately relies upon the release of metal cations into the local environment in order to provide any antimicrobial efficacy. Unfortunately, such metal cations, including heavy metal cations, ultimately make their way into the larger environment with undesirable consequences because of their fundamentally and indiscriminately toxic nature.
Noticeably absent in the art is any known or proposed mechanism for applying nanoparticles onto fibers in such a way that the desired nanoparticles remain adhered to the fibers until an active transport mechanism is presented that is capable of overcoming adhesive forces holding the particles onto the fabric surface. Such releasable adhesion of the nanoparticles to the fabric fibers would allow the nanoparticles to, at the appropriate time, go into solution without relying on a mechanism of ion release to provide antimicrobial efficacy.